What is Bell's palsy, its causes, and how is it treated in patients, particularly those with a history of conditions such as diabetes, high blood pressure, or a family history of Bell's palsy?

What is Bell's Palsy?

Bell's palsy is a sudden weakness or paralysis of one side of your face that happens when the facial nerve (the nerve that controls your facial muscles) becomes inflamed and swollen inside a narrow bone canal in your skull. 1, 2

How Your Face Will Look and Feel

When you have Bell's palsy, the entire affected side of your face stops working properly because the nerve that controls all the muscles on that side is compressed: 1

• Your forehead won't wrinkle when you try to raise your eyebrows 1, 3
• Your eye won't close completely on the affected side, even when you try hard 1, 3
• The corner of your mouth droops down and you may drool 4
• Your smile pulls only to the unaffected side 1
• The crease from your nose to your mouth flattens out 4

You may also experience: 1

• Pain around your ear or face on the affected side
• Changes in taste on the front part of your tongue
• Increased sensitivity to sound (things seem too loud)
• Dry eye or excessive tearing
• Difficulty eating or drinking

How Quickly Does It Happen?

The weakness develops rapidly—within 24 to 72 hours (1 to 3 days)—and this quick onset is a key feature of Bell's palsy. 1, 3 Most people notice the weakness is worst within the first week. 5

What Causes Bell's Palsy?

The honest answer is that we don't know the exact cause—that's why it's called "idiopathic," which means "of unknown cause." 1, 2 However, doctors suspect it involves inflammation and swelling of the facial nerve, possibly triggered by a viral infection (particularly herpes simplex virus type 1), though this remains unproven. 2, 5

What We Know About Risk Factors

Certain conditions increase your risk of developing Bell's palsy: 2

• Diabetes mellitus - People with diabetes have a higher risk, possibly due to nerve and blood vessel damage 2, 6
• Pregnancy - Especially in the third trimester 2
• High blood pressure - This is a recognized risk factor 6
• Recent upper respiratory infection - Having a cold or flu-like illness before Bell's palsy supports the viral theory 2
• Age - Most common between ages 15-45, though it can happen at any age 2
• Obesity - Increases risk 4
• Compromised immune system 2

Important: What Bell's Palsy Is NOT

Bell's palsy is a diagnosis of exclusion, meaning doctors must rule out other serious causes of facial weakness before confirming it's Bell's palsy. 1, 2 Your doctor needs to make sure you don't have: 1, 2

• Stroke - Distinguished because stroke spares the forehead (you can still wrinkle your forehead with a stroke)
• Brain tumors
• Lyme disease
• Herpes zoster (shingles affecting the face)
• Trauma or fractures
• Cancer involving the facial nerve
• Sarcoidosis or Guillain-Barré syndrome (especially if both sides of your face are affected)

How Long Does It Last and Will I Recover?

Most people recover completely within 3 to 6 months, even without treatment. 3, 5 The prognosis depends on how severe your paralysis is initially: 3

• If you have incomplete paralysis (some movement remains): Up to 94% recover completely 3
• If you have complete paralysis (no movement at all): Approximately 70% recover completely 3
• Most people begin showing improvement within 2-3 weeks 3

However, about 30% of patients may have some permanent facial weakness or muscle tightness. 3

Treatment: What You Need to Do

Immediate Treatment (Within 72 Hours)

You must start oral corticosteroids (prednisone or prednisolone) within 72 hours of symptom onset—this is the only proven effective treatment. 3, 7 The standard regimen is: 3

• Prednisone 60 mg daily for 5 days, then taper over 5 days, OR
• Prednisolone 50 mg daily for 10 days

Evidence shows this increases complete recovery from 64% to 83% at 3 months. 3

Your doctor may also offer antiviral medication (valacyclovir or acyclovir) in addition to steroids, though the added benefit is small. 3, 7 If prescribed: 7

• Valacyclovir 1 gram three times daily for 7 days, OR
• Acyclovir 400 mg five times daily for 10 days

Never take antivirals alone—they don't work without steroids. 3, 7

Critical Eye Protection (Start Immediately)

Because you cannot close your eye completely, you are at serious risk of permanent corneal (eye surface) damage. 1, 3 You must protect your eye aggressively: 3

• During the day: Use lubricating eye drops every 1-2 hours while awake 3
• At night: Apply thick eye ointment before bed 3
• Always: Wear sunglasses outdoors to protect from wind and particles 3
• If severe: Tape your eye closed at night (your doctor will show you the proper technique to avoid scratching your eye) 3

Seek immediate medical attention if you develop eye pain, vision changes, redness, or increasing irritation. 3

Special Considerations for Your Medical History

If You Have Diabetes

Your risk of Bell's palsy is higher, and you may have a slightly worse prognosis due to underlying nerve and blood vessel damage. 2, 6 However, treatment remains the same—steroids within 72 hours and aggressive eye protection. 3 Your blood sugar may increase temporarily with steroid treatment, so monitor it closely.

If You Have High Blood Pressure

High blood pressure is a risk factor for Bell's palsy, but treatment is unchanged. 6 Steroids may temporarily raise your blood pressure, so monitor it during treatment.

If You Have a Family History of Bell's Palsy

While Bell's palsy can recur (about 10% of cases), family history alone doesn't change your treatment or prognosis. 2 However, if you develop Bell's palsy on the same side a second time, you will need imaging (MRI) to rule out a tumor. 3

Follow-Up Timeline

You must be reassessed at 3 months if you haven't fully recovered. 3 You need urgent evaluation at any time if you develop: 3

• New neurologic symptoms (weakness elsewhere, speech problems, confusion)
• Worsening facial weakness after initial improvement
• Eye symptoms despite protection measures

Treatments That DON'T Work

Physical therapy and acupuncture have no proven benefit for Bell's palsy. 1, 3 Don't waste time or money on these approaches during the acute phase.

Long-Term Management (If Needed)

If you haven't recovered by 3 months, you should see a facial nerve specialist who can offer: 3

• Reconstructive surgery options (eyelid weights, facial slings, nerve transfers)
• Continued ophthalmology care for persistent eye closure problems
• Psychological support, as persistent facial paralysis significantly impacts quality of life and can lead to depression 3

Common Pitfalls to Avoid

• Don't delay treatment beyond 72 hours—steroids lose effectiveness after this window 3
• Don't neglect eye protection—this can cause permanent blindness 3
• Don't assume it's Bell's palsy if both sides of your face are affected—this requires urgent evaluation for other serious conditions 1, 2
• Don't accept antiviral medication alone—it doesn't work without steroids 3, 7